Percutaneous injuries, with their attendant risk of hepatitis, HIV, and other blood-borne illnesses, are the greatest occupational hazard faced by resident physicians and motor vehicle crashes (MVC) are the leading cause of death in their age group. In our nationwide survey of 2,737 resident physicians in their first postgraduate year (PGY1s) we found that extended duration work shifts (> 24 hours) were associated with a 73% increase in the risk of percutaneous injuries and a 168% increase in motor vehicle crashes (MVCs) on the commute from work. We found that PGY1s were also significantly more likely to report falling asleep while driving when they worked at least one or more extended duration shifts per month. Based on these and similar findings, in 2009, the Institute of Medicine (IOM) recommended and in 2011, the Accreditation Council for Graduate Medical Education (ACGME) implemented, a 16-hour limit on the number of consecutive hours that resident physicians may be scheduled to work in their first postgraduate year. In order to determine the effectiveness of the new work hour rule, we propose to conduct a large-scale nationwide survey of interns, similar to that which we conducted from 2002-2007. We will collect work hours and sleep data as well as health and safety outcomes on monthly web-based surveys. We propose to test the hypotheses that sleep will be increased, and the incidence rates of MVCs and percutaneous injuries will be decreased among PGY1 residents working under the new ACGME Common Program Requirements (2011) that limit the duration of work shifts to 16 consecutive hours as compared to data we previously collected from 6,487 PGY1s (47,858 monthly surveys) prior to implementation of this limit. We will also test the hypotheses that sleep will be increased and the incidence rates of MVCs and percutaneous injuries will be decreased among PGY1 residents whose work shifts are limited to 16 consecutive hours as compared to those same residents in their PGY2+ years who are scheduled to work extended duration (>24 hours) shifts. The proposed study could have important public policy implications related to the health and safety of the more than 108,000 medical and surgical residents, who are the principal providers of medical care in academic medical centers throughout the United States.